Focusing manipulation of microalgae in a microfluidic device using self-produced macromolecules†
Extracellular polymeric substances (EPSs) are self-produced biosynthetic macromolecules that have a three-dimensional architecture in bacterial biofilms and are mainly composed of a mixture of polysaccharides, proteins and nucleic acids. Compared with synthetic polymers, EPSs can have a long relaxation time due to their structural complexity. We exploited the non-Newtonian rheological behavior of EPSs extracted from Chlorella vulgaris with the help of cell focusing and particle focusing in confined microchannels. The microalgae showed a ‘self-ordering’ behavior in the ‘self-secreted’ substances. The EPSs were characterized and analyzed chemically and rheologically. In a microfluidic device, they enable outstanding particle focusing over a wide range of flow rates. This study can open an effective, unique pathway for applications of biomass related resources such as EPSs.